He explains how the "Chinese don't sit on benches while eating but squat like Europeans do when they relieve themselves out in the leafy woods. All this occurs quietly and demurely. Even the children are spiritless and look obtuse."

"It would be a pity if these Chinese supplant all other races. For the likes of us the mere thought is unspeakably dreary."

Ze'ev Rosenkranz, assistant director of the California Institute of Technology's Einstein Papers Project, said: "I think a lot of comments strike us as pretty unpleasant - what he says about the Chinese in particular.

"They're kind of in contrast to the public image of the great humanitarian icon. I think it's quite a shock to read those and contrast them with his more public statements. They're more off guard, he didn't intend them for publication."

Rosekranz, who translated and edited "The Travel Diaries of Albert Einstein", said, "I'm not apologizing for him or anything. … I still feel that the unpleasant remarks are quite shocking, but they do reveal that we all have this darker side to our attitudes and prejudices."

Naturally, people were shocked to find that such a pillar of modern science had such abhorrent views, particularly when he had been such an outspoken critic of the oppression of African-Americans.

"There is separation of colored people from white people in the United States. That separation is not a disease of colored people. It is a disease of white people. I do not intend to be quiet about it," Einstein said during a 1946 commencement speech at Lincoln University in Pennsylvania.

BBC Washington correspondent Chris Buckler wrote that Einstein's eyes may have been opened to racism when he was forced to flee Nazi Germany:

"He is said to have told people that he saw similarities in the way Jews were being hounded in Germany and how African-Americans were being treated in his new homeland.

"His diaries are full of gut reactions and private insights. In the context of the 21st Century, they may tarnish the reputation of a man who is revered almost as much as a humanitarian as a scientist.

"But the words were written before he saw what racism could lead to in America and Germany - a country he had effectively fled."

Other commentators were not quite so forgiving of the famous physicist:

"China was poor and lagging behind, sometimes there were famines, most of the people were illiterate… Babies died young so people had to have more children to ensure survival. It's hard not to discriminate against a China like this," wrote one user on Chinese social media site Weibo.

"I don't think these are racist comments or humiliating descriptions," wrote Siguan Xuantang on Weibo. "It's more like a description of facts. Just look at the economic status, education, and hygiene conditions, which most of the common people wouldn't care that much about because they didn't have the conditions… He described them as obtuse and blunt but he also said people were industrious."